So far it is bugged on orc side but here are the details on this quest. (Disturbing the enemy nation)
*talk to adviser in back of town
*He give you a scroll which will allow you to invade opposite nation.
-You can't use skills
-You may not defend yourself or go invisible.
-You have to sneak into main castle and steal the secret documents located at the back of the castle.
*When you finish this quest he will give you a (war trophy) item
*This war trophy can be turned in to operator (miora) for a random item.
*A notice will appear at the top of the screen which will say Enemies invaded, when you have entered the opposite nation's land.
*This quest can be done (once) every day. (With success only and as many times as you want if you fail.)
** I'm not sure what the trophy gives you when you turn it in. (hopefully good uniques)